He3D Delta printer setup and initial homing

I've assembled an He3D delta-180 printer. It would be nice to actually use it. ;)

It had repetier firmware originally installed that seemed to function in a limited fashion (some movements worked, but a G28 Home caused it to go beserk at the endstops), so I decided to update it with the copy of repetier firmware that came on the media with the printer. And that's when the wheels really fell off. Whatever that software was, it was 500% worse that what had been pre-installed. After HOURS and HOURS of searching the web, I finally found someone that had a version of Marlin that was supposed to work for this model printer. And it does, to a degree. Much better than any of the other repetier (or even generic Marlins) that I'd tried. BUT, it's still not functional.

I knew nothing about Arduino, RAMPS, or 3D printers when I started this adventure, and I have learned tons in the last few months as I try to ferret out how to make this work. I think I've reached the limit of what I can decipher myself or piece together from other peoples questions and answers. So, here I am.

My biggest obstacle continues to be that the printer won't home. I've never been able to get past that most basic of steps.

I'm running Marlin 1.0.x

When I give the printer the G28 command, all the carriages climb toward the top. The first carriage to hit an endstop will immediately back off, then retry the endstop. At this point, that carriage ignores the endstop and tries to continue climbing, causing the belt to jump and make a racket. After a few seconds, it will again backoff and set. Then another carriage will climb to the endstop, and stop appropriately. The third carriage (lowest) will not move after the inital endstop is triggered.

I thought maybe the one of the endstops were bad, or miswired, or open/close reversed, but M119 commands show the proper triggering when tested manually.

It also doesn't appear to be a set column carriage that is at issue. If I maneuver the head slightly so that a different column touches its endpoint first, then the pattern repeats with the new highest (first hitting) column to be the one to beIlt jump, lowest doesn't move. And again, if I maneuver to have the last column highest, it will be the one that belt jumps and the lowest fails to move to the endstop.

I can't find anything in configuration.h that explains this behavior, and even starting tracing the program itself to see if I could decipher what could be causing this particular pattern. I haven't given up on that yet, but it is slow going and decided to post instead. The printer acts like Marlin has a bad array counter and does the first element twice and never get's to the third.

Any ideas on how to determine what's causing this?

I did see that there is a release candidate of Marlin available, so i'm going to give that a whirl and see if it makes any difference.

Also, I didn't see a Marlin specific forum, so if there is someplace else (either here, or on another site) that would get better exposure to Marlin delta-printer users, please let me know.

Thanks!

I get to answer my own question. w00t! Turns out two tower axis endstops were not matched up properly. It was very strange because when I did endpoint tests with m119 I was getting the "correct" values which seemed to be on the correct axis. The revelation came when when I decided to run a G28 home and manually trigger the endstops before the carriages reached the top (so I could easily see which ones stopped when). It became very obvious that the carriage that stopped was not the endpoint that was triggered. I swapped two towers and the system starting homing properly. What an ordeal of frustration for something as simple as a mis-wire! Hope this helps someone else.

As a side note, I switched back to repetier. I liked it's screen interface better anyway, and read several posts that indicated it handled "out of square" issues better, which I suspect I may run into as I continue.

Still haven't printed anything though, because I'm now faced with extruder jamming problems.